.. auto-generated by script ../../../../utils/nxdl2rst.py from the NXDL source ../../../../base_classes/NXsource.nxdl.xml

.. index::
    ! NXsource (base class)
    ! source (base class)
    see: source (base class); NXsource

.. _NXsource:

========
NXsource
========

**Status**:

  base class, extends :ref:`NXobject`, version 1.0

**Description**:

  Template of the neutron or x-ray source, insertion devices and/or moderators.

**Symbols**:

  No symbol table

**Groups cited**:
  :ref:`NXdata`, :ref:`NXgeometry`, :ref:`NXnote`

.. index:: NXnote (base class); used in base class, NXdata (base class); used in base class, NXgeometry (base class); used in base class

**Structure**:

  .. index:: distance (data field)

  **distance**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    Effective distance from sample
    Distance as seen by radiation from sample. This number should be negative 
    to signify that it is upstream of the sample.

  .. index:: name (data field)

  **name**: :ref:`NX_CHAR <NX_CHAR>`

    Name of source

    .. index:: short_name (attribute)

    **@short_name**: :ref:`NX_CHAR <NX_CHAR>`

      short name for source, perhaps the acronym

  .. index:: type (data field)

  **type**: :ref:`NX_CHAR <NX_CHAR>`

    type of radiation source (pick one from the enumerated list and spell exactly)

    Any of these values:

      * ``Spallation Neutron Source``

      * ``Pulsed Reactor Neutron Source``

      * ``Reactor Neutron Source``

      * ``Synchrotron X-ray Source``

      * ``Pulsed Muon Source``

      * ``Rotating Anode X-ray``

      * ``Fixed Tube X-ray``

      * ``UV Laser``

      * ``Free-Electron Laser``

      * ``Optical Laser``

      * ``Ion Source``

      * ``UV Plasma Source``


  .. index:: probe (data field)

  **probe**: :ref:`NX_CHAR <NX_CHAR>`

    type of radiation probe (pick one from the enumerated list and spell exactly)

    Any of these values:

      * ``neutron``

      * ``x-ray``

      * ``muon``

      * ``electron``

      * ``ultraviolet``

      * ``visible light``

      * ``positron``

      * ``proton``


  .. index:: power (data field)

  **power**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_POWER <NX_POWER>`}

    Source power

  .. index:: emittance_x (data field)

  **emittance_x**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_EMITTANCE <NX_EMITTANCE>`}

    Source emittance (nm-rad) in X (horizontal) direction.

  .. index:: emittance_y (data field)

  **emittance_y**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_EMITTANCE <NX_EMITTANCE>`}

    Source emittance (nm-rad) in Y (horizontal) direction.

  .. index:: sigma_x (data field)

  **sigma_x**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    particle beam size in x

  .. index:: sigma_y (data field)

  **sigma_y**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    particle beam size in y

  .. index:: flux (data field)

  **flux**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_FLUX <NX_FLUX>`}

    Source intensity/area (example: s-1 cm-2)

  .. index:: energy (data field)

  **energy**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_ENERGY <NX_ENERGY>`}

    Source energy.  
    For storage rings, this would be the particle beam energy.
    For X-ray tubes, this would be the excitation voltage.

  .. index:: current (data field)

  **current**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_CURRENT <NX_CURRENT>`}

    Accelerator, X-ray tube, or storage ring current

  .. index:: voltage (data field)

  **voltage**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_VOLTAGE <NX_VOLTAGE>`}

    Accelerator voltage

  .. index:: frequency (data field)

  **frequency**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_FREQUENCY <NX_FREQUENCY>`}

    Frequency of pulsed source

  .. index:: period (data field)

  **period**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_PERIOD <NX_PERIOD>`}

    Period of pulsed source

  .. index:: target_material (data field)

  **target_material**: :ref:`NX_CHAR <NX_CHAR>`

    Pulsed source target material

    Any of these values:

      * ``Ta``

      * ``W``

      * ``depleted_U``

      * ``enriched_U``

      * ``Hg``

      * ``Pb``

      * ``C``


  .. index:: number_of_bunches (data field)

  **number_of_bunches**: :ref:`NX_INT <NX_INT>`

    For storage rings, the number of bunches in use.

  .. index:: bunch_length (data field)

  **bunch_length**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_TIME <NX_TIME>`}

    For storage rings, temporal length of the bunch

  .. index:: bunch_distance (data field)

  **bunch_distance**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_TIME <NX_TIME>`}

    For storage rings, time between bunches

  .. index:: pulse_width (data field)

  **pulse_width**: :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_TIME <NX_TIME>`}

    temporal width of source pulse

  .. index:: mode (data field)

  **mode**: :ref:`NX_CHAR <NX_CHAR>`

    source operating mode

    Any of these values:

      * ``Single Bunch``: for storage rings

      * ``Multi Bunch``: for storage rings


  .. index:: top_up (data field)

  **top_up**: :ref:`NX_BOOLEAN <NX_BOOLEAN>`

    Is the synchrotron operating in top_up mode?

  .. index:: last_fill (data field)

  **last_fill**: :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_CURRENT <NX_CURRENT>`}

    For storage rings, the current at the end of the most recent injection.

    .. index:: time (attribute)

    **@time**: :ref:`NX_DATE_TIME <NX_DATE_TIME>`

      date and time of the most recent injection.

  **notes**: :ref:`NXnote`

    any source/facility related messages/events that 
    occurred during the experiment

  **bunch_pattern**: :ref:`NXdata`

    For storage rings, description of the bunch pattern.  
    This is useful to describe irregular bunch patterns.

    .. index:: title (data field)

    **title**: :ref:`NX_CHAR <NX_CHAR>`

      name of the bunch pattern

  **pulse_shape**: :ref:`NXdata`

    source pulse shape

  **geometry**: :ref:`NXgeometry`

    "Engineering" location of source

  **distribution**: :ref:`NXdata`

    The wavelength or energy distribution of the source

**Source**:
  Automatically generated from https://github.com/nexusformat/definitions/blob/master/base_classes/NXsource.nxdl.xml